Explain the differences between CHAR and VARCHAR

CHAR(n):

• Stores fixed-length strings of length n.
• If the entered string is shorter than n, it is padded with spaces to reach the length of n.
• Used for storing data of uniform length (e.g., country codes, postal codes).

VARCHAR(n):

• Stores variable-length strings up to n characters.
• Actually occupies as much space as the number of characters in the string plus a small overhead for storing the length.
• Used for storing string data of variable length.

Key differences:

Memory and performance:

• CHAR always occupies a fixed amount of memory.
• VARCHAR is more memory-efficient but may be slightly slower in access.

Usage:

• CHAR is suitable for data with predictable length.
• VARCHAR is suitable for data with variable length.

Example:

MySQL 8.1
CREATE TABLE products (
    code CHAR(10),     -- Fixed-length product code
    name VARCHAR(100)  -- Variable-length product name
);

Inserting data:

MySQL 8.1
INSERT INTO products (code, name)
VALUES ('A123', 'Lenovo Laptop');

In the code column, the value will be padded with spaces up to 10 characters.